Impact of non-binder ingredients and molecular weight of polymer binders on heat assisted twin screw dry granulation

Thermal degradation of Affinisol HPMC: Optimum Processing Temperatures for Hot Melt Extrusion and 3D Printing

PURPOSE

Affinisol HPMC HME is a new popular form of hypromellose specifically designed for the hot melt extrusion and 3D printing of pharmaceutical products. However, reports of its thermal stability include only data obtained under inert N2 atmosphere, which is not consistent with the common pharmaceutical practice. Therefore, detailed investigation of its real-life thermal stability in air is paramount for identification of potential risks and limitations during its high-temperature processing.

METHODS

In this work, the Affinisol HPMC HME 15LV powder as well as extruded filaments will be investigated by means of thermogravimetry, differential scanning calorimetry and infrared spectroscopy with respect to its thermal stability.

RESULTS

The decomposition in N2 was proceeded in accordance with the literature data and manufacturer's specifications: onset at ~260°C at 0.5°C·min-1, single-step mass loss of 90-95%. However, in laboratory or industrial practice, high-temperature processing is performed in the air, where oxidation-induced degradation drastically changes. The thermogravimetric mass loss in air proceeded in three stages: ~ 5% mass loss with onset at 150°C, ~ 70% mass loss at 200°C, and ~ 15% mass loss at 380°C. Diffusion of O2 into the Affinisol material was identified as the rate-determining step.

CONCLUSION

For extrusion temperatures ≥170°C, Affinisol exhibits a significant degree of degradation within the 5 min extruder retention time. Hot melt extrusion of pure Affinisol can be comfortably performed below this temperature. Utilization of plasticizers may be necessary for safe 3D printing.

Chrono modulated multiple unit particulate systems (MUPS) via a continuous hot melt double extrusion technique: Investigation of the formulation and process suitability

The current study is aimed at the development of chrono modulated multiple unit particulate systems (MUPS) of nifedipine (ND) by a continuous double extrusion process. ND, a poorly soluble drug was formulated into an amorphous solid dispersion (ASD) to improve its solubility. Further, the ASD was converted into MUPS to control the drug release through a combination of pulsatile and sustained release portions. In the preparation of the ASD, the polymer HPMCAS LG was employed at different concentrations. MUPS were formulated by using Eudragit® FS100, Eudragit® RSPO, Klucel™ HF and lipids Precirol® ATO 5, Geleol™, Compritol® ATO5. The differential scanning calorimetry and powder X-ray diffraction studies of MUPS revealed the amorphous nature of ND. Scanning electron microscopy (SEM) studies depicted the surface morphology of the ASD and the gradual change in the surface of the coated MUPS during in-vitro release studies. The in-vitro drug release profiles of ASD indicated significant improvement (p < 0.05) of solubility of ND and MUPS demonstrated a combination of pulsatile and zero-order controlled release up to 12 h. Accelerated stability studies for MUPS at 40 °C/75% RH revealed the formulations were stable. These findings suggest hot melt double extrusion as a potential alternative for conventional techniques to produce MUPS.

Impact of hydrophilic binders on stability of lipid-based sustained release matrices of quetiapine fumarate by the continuous twin screw melt granulation technique

Dose dumping is the major drawback of sustained release (SR) matrices. The current research aimed to develop the stable lipid-based SR matrices of quetiapine fumarate (QTF) using Geleol™ (glyceryl monostearate; GMS) as the lipid matrix carrier and Klucel™ EF (HPC EF), Kollidon® VA64, and Kollidon® 12PF as hydrophilic binders. Formulations were developed using advanced twin screw melt granulation (TSMG) approach and the direct compression (DC) technique. Compared with the blends of DC, the granules of TSMG exhibited improved flow properties and tabletability. Solid-state characterization by differential scanning calorimetry of the prepared granules exhibited the crystalline nature of the lipid. Fourier transform infrared spectroscopy demonstrated no interaction between the formulation ingredients. The compressed matrices of TSMG and DC resulted in the sustained release of a drug over 16-24 h. Upon storage under accelerated conditions for 6 months, the matrices of TSMG retained their sustained release characteristics with no dose dumping in alcohol, whereas the matrices of DC resulted in the dose dumping of the drug attributing to the loss of matrix integrity and phase separation of lipid. Thus, it is concluded that the uniform distribution of a softened binder into a molten lipid carrier results in the stable matrices of TSMG.

Twin-Screw Melt Granulation for Oral Solid Pharmaceutical Products

This article highlights the advantages of pharmaceutical continuous melt granulation by twin-screw extrusion. The different melt granulation process options and excipients are described and compared, and a case is made for expanded use of twin-screw melt granulation since it is a flexible and continuous process. Methods for binder selection are profiled with a focus on rheology and physical stability impacts. For twin-screw melt granulation, the mechanism of granulation and process impact on granule properties are described. Pharmaceutical applications of melt granulation ranging from immediate release of soluble and insoluble APIs, taste-masking, and sustained release formulation are reviewed, demonstrating the range of possibilities afforded by twin-screw melt granulation.

Process optimization of twin-screw melt granulation of fenofibrate using design of experiment (DoE)

The purpose of this study was to optimize the melt granulation process of fenofibrate using twin-screw granulator. Initial screening was performed to select the excipients required for melt granulation process. A 3 × 3 factorial design was used to optimize the processing conditions using the % drug loading (X₁) and screw speed (X₂) as the independent parameters and granule friability (Y₁) % yield (Y₂) as the dependent parameters. The effect of the independent parameters on the dependent parameters was determined using response surface plots and contour plots. A linear relationship was observed between % drug loading (X₁) and % friability (Y₁) and a quadratic relationship was observed between the independent parameters (X₁ and X₂) and % yield (Y₂). The processing conditions for optimum granules were determined using numerical and graphical optimization and it was found that 15% drug loading at 50 rpm results in maximum % yield of 82.38% and minimum friability of 7.88%. The solid-state characterization of the optimized granules showed that the drug turned from crystalline state to amorphous state during melt granulation process. The optimized granules were compressed into tablets using Purolite® as the super disintegrating agent. The optimized formulation showed >85% drug release in 0.75% SLS solution within 60 min.

Pre-plasticization of thermal binder facilitates processing and granule growth during melt granulation of gabapentin using co-rotating twin screw extruder

Plasticization, a common method of reducing the polymer melt viscosity in plastics extrusion, was investigated to improve the processability of a pharmaceutical formulation during twin-screw melt granulation. The thermolabile drug gabapentin was used as a model compound given previous work showed the benefit of preparing 80% drug loading gabapentin granules with hydroxypropyl cellulose as thermal binder. The plasticizer triethyl citrate was selected based on physicochemical compatibility with both the thermal binder and gabapentin by assessing polymer melt rheology and drug stability, respectively. Gabapentin was melt granulated at 80% drug loading with pre-plasticized binder using a co-rotating twin-screw extruder. The chemical stability and tabletability of the pre-plasticized granules were assessed to evaluate granule tabletability, drug stability, and process robustness. The granulation of gabapentin was facilitated by pre-plasticization, showing both increased granule growth and the ability to optimize processing conditions by lowering processing temperature. Pre-plasticization of thermal binder was therefore shown to be beneficial during melt granulation as a method of optimizing processing conditions while maintaining granule robustness.

Effect of Hydroxypropyl Cellulose Level on Twin-Screw Melt Granulation of Acetaminophen

This study investigated the effect of binder level on the physicochemical changes and tabletability of acetaminophen (APAP)-hydroxypropyl cellulose (HPC) granulated using twin-screw melt granulation. Even at 5% HPC level, the tablet tensile strength achieved up to 3.5 MPa. A minimum of 10% HPC was required for the process robustness. However, 20% HPC led to tabletability loss, attributable to the high mechanical strength of APAP granules. The over-granulated APAP granules had thick connected HPC scaffold and low porosity. Consequently, these granules were so strong that they underwent a lower degree of fracture under compression and higher elastic recovery during decompression. HPC was enriched on the surface of APAP extrudates at all HPC levels. Amorphous APAP was also observed on the extrudate surface at 20% HPC level, and it recrystallized within 24 h storage. To achieve a robust process and optimal improvement in APAP tabletability, the preferred HPC level was 10 to 15%.

Twin-screw melt granulation: Current progress and challenges

Twin-screw melt granulation (TSMG) is a new alternative method for granulation that offers several advantages over wet and dry granulation methods. TSMG has rapidly gained interest over recent years in the pharmaceutical industry. Since it is an inherently continuous process with controlled temperature and shear history, TSMG produces products with more consistent quality than the batch process. Several studies have investigated how various formulation and processing parameters influence granulation behavior and granule properties; however, there are still challenges that require a better mechanistic understanding. This review summarizes the current progress of TSMG while highlighting how various formulation and process parameters affect the physicochemical properties of granules. The challenges related to the process-induced physicochemical changes of drug substances are also discussed.

Continuous twin screw granulation - An advanced alternative granulation technology for use in the pharmaceutical industry

Hot melt extrusion has been an exciting technology in the pharmaceutical field owing to its novel applicability. Twin-screw granulation presents a great potential and offers many advantages relative to conventional granulation processes. Different twin-screw granulation techniques, such as twin-screw dry granulation, twin-screw wet granulation, and twin-screw melt granulation, are currently being developed as robust and reproducible granulation processes. The competence of twin-screw granulation as a continuous manufacturing process has contributed to its suitability as an alternative granulation option within the pharmaceutical industry. In this article, different types of twin-screw granulation techniques were discussed. In addition, the screw elements, scale-up process, continuous twin-screw granulation which involves process analytical tools, and excipients were explored. This economical, industrially scalable process can be automated for continuous manufacturing to produce granules for the development of oral solid dosage forms. However, extensive research using process analytical tools is warranted to develop processes for the continuous manufacture of granules.

An update on the contribution of hot-melt extrusion technology to novel drug delivery in the twenty-first century: part II

INTRODUCTION

Interest in hot-melt extrusion (HME) technology for novel applications is growing day by day, which is evident from several hundred publications within the last 5 years. HME is a cost-effective, solvent free, 'green' technology utilized for various formulations with low investment costs compared to conventional technologies. HME has also earned the attention of the pharmaceutical industry by the transformation of this technology for application in continuous manufacturing.

AREAS COVERED

Part II of the review focuses on various novel opportunities or innovations of HME such as multiple component systems (co-crystals, co-amorphous systems and salts), twin-screw granulation, semi-solids, co-extrusion, abuse deterrent formulations, solid self-emulsifying drug delivery systems, chronotherapeutic drug delivery systems, and miscellaneous applications.

EXPERT OPINION

HME is being investigated as an alternative technology for preparation of multicomponent systems such as co-crystals and co-amorphous techniques. Twin-screw granulation has gained increased interest in preparation of granules via twin-screw melt granulation or twin-screw dry granulation. This novel application of the HME process provides a promising alternate approach in the formulation of granules and solid dosage forms. However, this technology may need to be further investigated for scalability aspects of these novel applications for industrial production.

Effects of thermal binders on chemical stabilities and tabletability of gabapentin granules prepared by twin-screw melt granulation

The effect of thermal binders on the physicochemical properties of gabapentin, a thermally labile drug, in granules prepared using twin-screw melt granulation was investigated in this study. Hydroxypropyl cellulose (HPC), a thermoplastic high molecular-weight binder, was compared against conventional low molecular-weight semi-crystalline thermal binders PEG 8000 and Compritol. Both the chemical degradation and polymorph form change of gabapentin were analyzed. The effects of particle size and molecular weight of HPC on the properties of granules were also studied. To overcome the high melt viscosity of HPC, higher barrel temperatures and higher specific mechanical energy were required to attain suitable granules. As a result, higher levels of gabapentin degradant were observed in HPC-based formulations. However, gabapentin form change was not observed in all formulations. Smaller particle size and lower molecular weight of HPC led to faster granule growth. The tabletability of granules was insensitive to the variations in particle size and molecular weight of HPC. Gabapentin crystal size reduction, HPC size reduction, and HPC enrichment on granule surface were observed for HPC-based granules.

Exploratory studies in heat-assisted continuous twin-screw dry granulation: A novel alternative technique to conventional dry granulation

Dry granulation is the preferred technique for solvent-sensitive products, especially drugs with stability problems such as hydrolysis. Twin-screw granulation is a continuous granulation technique, offering a potential alternative to conventional dry granulation techniques such as roller compaction. The major advantage of twin-screw granulation is the ability to adjust process parameters of dry granulation without compromising the compression properties. This study was aimed to perform exploratory studies of heat-assisted continuous twin-screw dry granulation process to formulate sustained release tablets for APIs with different melting points: theophylline, acetaminophen and lidocaine hydrochloride hydrate. Granulation feasibility was studied with different binders (e.g. Klucel™ EF, Kollidon® VA64), sustained release agents (e.g. Klucel™ MF, Eudragit® RSPO) and diluents at various drug loads. The processing conditions were below the melting point or glass transition temperature of the formulation ingredients. After successful granulation, DSC and XRD studies revealed the crystalline nature of the granules and FTIR studies showed no interaction of the API with the excipients. The granules were compressed into sustained release tablets without any compressibility issues. The tablets were stable after testing for 6 months at 25 °C/60% RH. This novel continuous dry granulation technique may offer an excellent alternative to conventional dry granulation techniques.